I want to get a call from somebody and after talking with him redirect that person to another number, on my charge, like call-centers do. Is that possible and if that's so, there is any application that can do that?

The feature you're looking for is known as call transfer. It's pretty common on office PBX and VoIP systems, but is virtually never seen with mobile phones. The existence of such a feature would require some intelligence in both the device and cooperation from the carrier's equipment, both of which are generally absent. As far as I know, there is nothing in the Android source code to support this feature.

While it may not be exactly what you're looking forward to, Google Voice has something like this.

If a caller calls your google voice number, all the phone you have registered ring at once. So you pick up the call on your home phone, then decide you want to go out. Google Voice lets you press 4, and it starts ringing the other phones again (without the other caller hearing anything). All you do is pick up the cell phone, and your call is transferred seamlessly.

I only post this in case someone is looking for this specific solution. Otherwise, you'll have to host your own PBX (like Asterisk) and set it up yourself. Android (well, specifically the cell carrier) doesn't have this option.